package com.resource.utils.sign;

import java.io.IOException;
import java.io.InputStream;
import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;

/**
 * 金融网关认证签名工具类
 * 
 * @Author: xianggaoxiong
 * @Date: 2020-11-03 10:59
 **/
public abstract class DigestUtils {
	private static final String MD5_ALGORITHM_NAME = "MD5";
	private static final char[] HEX_CHARS = new char[] { '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 'a', 'b',
			'c', 'd', 'e', 'f' };

	public DigestUtils() {
	}

	public static byte[] md5Digest(byte[] bytes) {
		return digest("MD5", bytes);
	}

	public static byte[] md5Digest(InputStream inputStream) throws IOException {
		return digest("MD5", inputStream);
	}

	public static String md5DigestAsHex(byte[] bytes) {
		return digestAsHexString("MD5", bytes);
	}

	public static String md5DigestAsHex(InputStream inputStream) throws IOException {
		return digestAsHexString("MD5", inputStream);
	}

	public static StringBuilder appendMd5DigestAsHex(byte[] bytes, StringBuilder builder) {
		return appendDigestAsHex("MD5", bytes, builder);
	}

	public static StringBuilder appendMd5DigestAsHex(InputStream inputStream, StringBuilder builder)
			throws IOException {
		return appendDigestAsHex("MD5", inputStream, builder);
	}

	private static MessageDigest getDigest(String algorithm) {
		try {
			return MessageDigest.getInstance(algorithm);
		} catch (NoSuchAlgorithmException var2) {
			throw new IllegalStateException("Could not find MessageDigest with algorithm \"" + algorithm + "\"", var2);
		}
	}

	private static byte[] digest(String algorithm, byte[] bytes) {
		return getDigest(algorithm).digest(bytes);
	}

	private static byte[] digest(String algorithm, InputStream inputStream) throws IOException {
		MessageDigest messageDigest = getDigest(algorithm);
		if (inputStream instanceof UpdateMessageDigestInputStream) {
			((UpdateMessageDigestInputStream) inputStream).updateMessageDigest(messageDigest);
			return messageDigest.digest();
		} else {
			byte[] buffer = new byte[4096];
			boolean var4 = true;

			int bytesRead;
			while ((bytesRead = inputStream.read(buffer)) != -1) {
				messageDigest.update(buffer, 0, bytesRead);
			}

			return messageDigest.digest();
		}
	}

	private static String digestAsHexString(String algorithm, byte[] bytes) {
		char[] hexDigest = digestAsHexChars(algorithm, bytes);
		return new String(hexDigest);
	}

	private static String digestAsHexString(String algorithm, InputStream inputStream) throws IOException {
		char[] hexDigest = digestAsHexChars(algorithm, inputStream);
		return new String(hexDigest);
	}

	private static StringBuilder appendDigestAsHex(String algorithm, byte[] bytes, StringBuilder builder) {
		char[] hexDigest = digestAsHexChars(algorithm, bytes);
		return builder.append(hexDigest);
	}

	private static StringBuilder appendDigestAsHex(String algorithm, InputStream inputStream, StringBuilder builder)
			throws IOException {
		char[] hexDigest = digestAsHexChars(algorithm, inputStream);
		return builder.append(hexDigest);
	}

	private static char[] digestAsHexChars(String algorithm, byte[] bytes) {
		byte[] digest = digest(algorithm, bytes);
		return encodeHex(digest);
	}

	private static char[] digestAsHexChars(String algorithm, InputStream inputStream) throws IOException {
		byte[] digest = digest(algorithm, inputStream);
		return encodeHex(digest);
	}

	private static char[] encodeHex(byte[] bytes) {
		char[] chars = new char[32];

		for (int i = 0; i < chars.length; i += 2) {
			byte b = bytes[i / 2];
			chars[i] = HEX_CHARS[b >>> 4 & 15];
			chars[i + 1] = HEX_CHARS[b & 15];
		}

		return chars;
	}
}
